Magnetic media formatted with an intergrated thin film subgap subpole structure for arbitrary gap pattern magnetic recording head

ABSTRACT

An arbitrary gap thin film magnetic recording head is fabricated by forming a substrate based on traditional vertical planar thin film head wafer technology which is designed to produce an integrated subgap and subpole substrate structure. The wafer is then processed into row bars to reveal, in a plane parallel to the transducing direction of the medium, the subgap and subpoles at the surface of the row bar and to bring the structure to a certain coil depth or gap depth. A flat or cylindrical contour may be utilized. 
     This thin film subgap row bar is taken through a film deposition or growth process that deposits the magnetic film on a plane perpendicular to the wafer plane, horizontal planar processing, forming a surface film recording head where an arbitrary gap structure can be made in-between the subpoles and generally directly on top of the subgap. The surface thin film is deposited and patterned on the tape bearing surface of the head to optimize various element configurations, gap patterns and head-to-tape medium contact. 
     An arbitrary gap thin film magnetic recording head is manufactured using two major thin film processing planes, one orthogonal to the other, the first major plane is wafer level and the second major plane is sub-wafer level and perpendicular to the first. The first major plane of processing defines the magnetically active substrate including coils, subgap and subpole members. The second major plane of processing defines the surface film which transmits the flux from the subpoles to the gap features contained in the surface film. 
     This resulting structure is a recording head that is wired to the servo system electronics and will format the tape with the arbitrary gap pattern.

FIELD OF THE INVENTION

This invention relates generally to magnetic recording heads and moreparticularly to head designs for the manufacture of heads with arbitraryshaped gaps used in high density tape data storage systems where suchdata storage systems may require complex arbitrary gap structures as inthe case of servo format heads, advanced servo heads to enable patternsfor the future or advanced angled gap write heads as in the case ofazimuthal recording schemes.

BACKGROUND OF THE INVENTION

While a variety of data storage mediums are available, magnetic taperemains a preferred technology for economically storing large amounts ofdata. To facilitate the efficient use of this particular magneticmedium, magnetic tape is widely used in so-called multi-channel, lineartape format in which a plurality of servo and data tracks extend in thelongitudinal direction of the tape. Magnetic track transitions embodyingrecorded data or servo information may be written into tracks with avariety of orientations.

After one or more write elements record data on the tape, one or moredata heads containing one or more read elements will read the data fromthose tracks as the tape advances in the longitudinal or transducingdirection in which the magnetic transitions move past the head to beread back. It is generally not feasible to provide a dedicated head orelement for each data track, therefore, a multi-channel head(s) mustmove across the width of the tape, and each data channel head elementaccesses a large number of data tracks dedicated specifically to thathead channel element. At each track the element must be accuratelycentered over the data track. In very high density cases this cannot beachieved by mechanical means alone, and a track following servo isemployed where dedicated servo read elements read a band of prerecordedservo tracks which correspond to specific data tracks in each data bandassociated with a given data (read or write) element. The servo band isused in controlling the translational movement of the head(s). The servoband is used not only to position the head(s) on the correct track butalso to keep it on the track once it has arrived at the track.

The servo track contains data, which when read by the servo readelement, is indicative of the relative position of the servo readelement with respect to the magnetic media in a translating direction.In one type of traditional amplitude based servo arrangement, the servotrack is divided in half. Servo data is recorded in each half track, atdifferent frequencies. The servo read element is approximately as wideas the width of a single half track. Therefore, the servo read elementdetermines its relative position by moving in a translating directionacross the two half tracks. The relative strength of a particularfrequency of servo signal would indicate how much of the servo readelement is located within that particular half track. The trend towardthinner and thinner magnetic tape layers causes amplitude modulationproblems with this and other amplitude based heads. That is, as thethickness of the magnetic layer decreases, normal variations on thesurface represent a much larger percentage variation in the magneticlayer, which may dramatically affect the output signal.

One type of servo control system was created which allows for a morereliable positional determination by reducing the amplitude based servosignal error traditionally generated by debris accumulation, mediathickness non-uniformity and head wear. U.S. Pat. No. 5,689,384(Albrecht, Barrett, and Eaton, IBM), incorporated herein by reference inits entirety, describes using a timing-based servo pattern on a magneticrecording head.

In a timing-based servo pattern, magnetic marks (transitions) arerecorded in pairs within the servo track. Each mark of the pair isangularly offset from the other. For example, a diamond pattern has beensuggested and employed with great success. The diamond extends acrossthe servo track in the translating direction. As the tape advances, theservo read element detects a signal or pulse generated by the first edgeof the first mark. Then, as the element passes over the second edge ofthe first mark, a signal of opposite polarity will be generated. Now, asthe tape progresses, no signal is generated until the first edge of thesecond mark is reached.

Once again, as the element passes the second edge of the second mark, apulse of opposite polarity is generated. This pattern is repeatedindefinitely along the length of the servo track.

Therefore, after the element has passed the second edge of the secondmark, it arrives at another pair of marks. The time it took to move fromthe first mark to the second mark is noted. Additionally, the time ittakes to move from the first mark (of the first pair) to the first markof the second pair is similarly noted.

The ratio of these two time components is indicative of the position ofthe read element within the servo track, in the translating direction.As the read head moves in the translating direction, this ratio variescontinuously because of the angular offset of the marks. It should benoted that the servo read element is relatively small compared to thewidth of the servo track. Ideally, the servo element is smaller than onehalf the width of a written data track. Because position is determinedby analyzing a ratio of two time/distance measurements, taken relativelyclose together, the system is able to provide accurate positional data,independent of the absolute speed of the media. In such systems, thevariations in the speed need to be relatively well controlled.

Once the position of the servo read element is accurately determined,the position of the various data read elements can be controlled andadjusted with a similar degree of accuracy on the same substrate.Namely, the various read elements are fabricated on the same substratewith a known and, generally, the same spacing between them. Hence,knowing the location of the servo element allows for a determination ofthe location of all the data elements.

When producing magnetic tape, or any other magnetic media, the servotrack is generally written by the manufacturer. This results in a moreconsistent and continuous servo track, over time. To write thetiming-based servo track described above, a magnetic recording headbearing the particular angular pattern as its gap structure is utilized.To achieve maximum accuracy in the servo positioning signal, it isnecessary to write a very accurate servo pattern. This means that a veryprecise servo recording element must be fabricated.

In the case of azimuthal recording schemes for linear multi-channeltape, as disclosed in the Large Angle Azimuthal Recording System(“LAAZR”) patents applied for by Schwarz and Dugas, having Ser. No.10/793,502, filed Mar. 4, 2004, which are incorporated in their entiretyby reference, there exists a need for arbitrary shaped gaps for theservo writing elements, as well as the write and read elements, to havelarge angle gap features. This later can be addressed by making a largeangle mechanical placement of non-angular thin film head row bars into aslider assembly. The proposed head of this invention may simplify theneed for the large angle mechanical placement and result in a simplerslider assembly, in particular for the write head of such a system.

Two general types of recording heads, each having the capability ofmultiple arbitrary slanted gap features, such as those for timing-baseservo patterns on tape media, are generally known. One type is a ferritecomposite substrate assembly with a horizontal surface film process andthe other type is that of a horizontally processed pure integrated thinfilm head.

The first type, perhaps the most simple, is a ferrite ceramic compositestructure as disclosed in U.S. Pat. No. 5,689,384 (Albrecht, Barrett,and Eaton, IBM), in U.S. Pat. No. 6,269,533 (Dugas, ARC) and U.S. Pat.No. 6,496,328 (Dugas, ARC).

The second type, a pure horizontal planar process thin film head, isdisclosed by Aboaf, Dennison, Friedman, Kahwaty, and Kluge in U.S. Pat.No. 5,572,392 and in U.S. Pat. No. 5,652,015. In these patents, theprocess is referred to as a single major plane process. That process isreferred to herein as Horizontal Planar Process (“HPP”) since the planeof processing in that head substrate lies parallel to the tape bearingsurface. Indeed the first type, the Albrecht reference and the Dugasreference heads also use the HPP approach; however, those heads are notfully integrated and use a composite ferrite/ceramic substrate structurewith a wound coil.

With a pure integrated thin film head, all of the components of the headare created from depositing and patterning different layers ofmaterials, as thin films, generally on a substrate. For example, themagnetic core, the windings and any low permeability barrier materialsare formed by producing thin films. In some designs which employ amagnetic substrate or wafer, such as Ni—Zn ferrite, this magneticsubstrate may end up as a shield or a pole or as part of a magneticyoke.

The integrated thin film head design and process of Aboaf is capable ofmultiple arbitrary slanted gaps as required of timing-base servo systemsprecisely because of the horizontal planar process used in that headconstruction. While this head solved the arbitrary gap limitation of thestandard thin film head industry process, such a head is extremelydifficult to manufacture and has not been produced commercially.

The typical integrated thin film tape or disk head process is hereinreferred to as a Vertical Planar Process (“VPP”) since the plane ofprocessing in that wafer is perpendicular or vertical to the tapebearing surface. This process is used almost exclusively in the thinfilm head industry. The VPP technique as used in data heads, as iseasily understood from the referenced patents, cannot make slanted gapsor pairs of oppositely slanted gaps as required by timing-base servoheads and complex azimuthal recording schemes. Hence, to date, pure thinfilm heads such as those that are made from VPP techniques are notsuitable for timing-based heads, and those made from a fully integratedHPP technology are not seen as practical to produce such a magnetichead, each for different reasons.

FIG. 1A is a side cross sectional view that shows a prior artconventional thin film VPP magnetic data head 100 for use in datarecording on magnetic media such as disks or tape. This head consists ofa generally non-magnetic substrate 110, a layer of polished alumina 111,a sputtered or plated first magnetic pole 112, an insulating gap layer120 which is generally alumina, coils 118, an insulating layer 117 whichencompasses coils 118, a second magnetic pole piece 114, a planarizedovercoat layer 122, and typically in the case of tape heads, anonmagnetic closure piece 124. A magnetic tape medium 126 moves in adirection as shown by arrow 128 operating in a motion transverse to thepoles pieces 112 and 114 and over a bearing surface 129. The head islapped to a gap depth 148 which is the distance from the tape bearingsurface 129 to the apex point 121 of the second pole 114 usuallyinvolving the use of lapping guides, made during the wafer fabricationprocess. Direction arrow 185 shows the direction of film layer growthfrom the wafer substrate surface.

Typically, VPP heads cannot be manufactured with a set of angled gaps asrequired for timing-based servo heads. This is shown in FIG. 1B which isa top view of the prior art of

FIG. 1A. The gap 120 of such a process is essentially planar or parallelto the wafer 110 surface. This makes it difficult, if not impossible, tomake an angled gap, and the extension to multiple angled gaps in onehead channel seems even more improbable.

An integrated horizontal magnetic head design solves this limitation ofplanar gaps. This head as shown in the cross section of FIG. 2A and thetop view of FIG. 2B, takes advantage of processing in a different majorplane from the head of FIG. 1. This head uses an HPP wafer constructionto distinguish it from the VPP wafer construction of the thin film headof FIG. 1.

With such an HPP approach, the arbitrary gap structures required fortiming-base servo systems can be realized. In addition to the previouscited Aboaf patents '392 and '015, other examples of this type of headinclude the head of U.S. Pat. No. 4,837,924, Jean-Pierre Lazzari, issuedon Jun. 13, 1989, and titled “Process For The Production Of PlanarStructure Thin Film Magnetic Recording Head,” and the head of U.S. Pat.No. 5,768,070, by Krounbi and Re, issued on Jun. 16, 1998, and titled“Horizontal Thin Film Write, MR Read Head.” These types of heads aresometimes referred to as “horizontal heads” in the industry.

Head 200 is illustrated in FIG. 2A, the magnetic back yoke 236 is eithera ceramic magnetic substrate or a deposited magnetically permeable layeron a ceramic substrate. One write element 232 is shown in cross section.Coil 238 is shown in a 4 turn configuration. Horizontal top poles 242 aand 242 b conduct the flux from the back yoke 236 to the main recordinggap 234 at the surface of the head. Feature 240 is a coil insulatinglayer. Typically a hard nitrided layer is used for the upper magneticfilm 242 b. Gap 234 can be defined on any arbitrary angle as shown inthe top planar view of FIG. 2B. Direction arrow 285 shows the directionof film growth from the substrate surface in FIG. 2A and FIG. 2B. Therecording medium is shown as 226 and moves in the direction as shown bythe arrow 228 in both FIGS. 2A and 2B.

Regarding the top view of FIG. 2B, the arbitrary gaps as shown areangled 234 b and straight 234 a. Coil 238 is shown in a 4 turnconfiguration. Each of the write elements 232 are shown coupled to acommon coil 238. The tape span 226 is shown to illustrate that headsupport structure and coil 238 extend outside the tape path and allowsfor the leads to be attached to bond pads 237.

The head just described in FIGS. 2A and 2B has the flexibility ofarbitrary gap angles.

However, it is not clear that the standard ion milling techniqueproposed to etch the gaps will result in good gap wall definition due tothe well known aspect ratio considerations in such a milling technique.Moreover, from a consideration of the layout of the coil upon thesurface plane as shown in FIG. 2B, it may be difficult to have eachwrite element 232 independently addressable with a separate coil.Bringing coil terminations and leads out of the tape bearing plane ofthe head may pose a design issue for the head assembly.

The surface film heads used commercially today for servo tape formattingof arbitrary angles gaps are made of structures and techniques proposedby the heads shown in FIGS. 3 and 4, respectively. These heads are madewith a horizontal planar or surface thin film process in combinationwith a ferrite/ceramic composite substrate. The substrate carries thesubgap embedded within it. The heads, as taught in '384, and in '328,are practical heads used to make arbitrary slanted gaps. These types ofheads are referred to herein as composite ferrite/ceramic surface filmheads.

Head 300 is illustrated in the prior art FIG. 3A. The compositeferrite/ceramic surface film head 300 includes two ferrite blocks 308,306 that are bonded to a ceramic member 311 that extends the entirewidth of the head 300. Surface 390 is contoured and polished inpreparation for film deposition. A magnetically permeable thin film 304is deposited over an upper surface 390 of the ferrite blocks 308, 306and the exposed upper portion of the ceramic member 311. Air slots 312serve to reduce air entrainment of the tape.

Servo writing gap patterns 314 are formed in the thin film 304, in awell defined arbitrary gap pattern. Winding 320 is wound around 306 andis electrically driven to produce magnetic flux around the ferrite core306 and through the thin film 304. The flux leaks from the gaps 314 andwrites media (not shown) passing over it.

The detail of the gap structure is shown in FIG. 3B. Gap pattern 314 iscomposed of angled gaps 330 and pattern termination feature 332.

This head has a rather large inductance and, therefore, relatively slowwrite current rise time. It is also a single drive element design thatserves to drive two or more servo elements made into the magnetic film304 spanning over the subgap formed by ceramic member 311. In this headflux can leak around the gap pattern as the flux is not well confined tothe recording gaps 314 unless the head is driven to saturation withextremely high current levels.

The inductance related rise time issues, the lack of independentlydriven write elements, and the writing uniformity issues were addressedsuccessfully by the prior art head design of patent '328. This head 400is illustrated in FIG. 4A and in detail in FIGS. 4A-4D.

Head 400 of FIGS. 4A-4D is made of a complex ferrite ceramic compositestructure as shown in FIG. 4A. As shown in the detail of single element450 of FIG. 4B, ferrite core pieces 408 and 406 form the driving polesabout a ceramic I-bar which serves as a non-magnetic subgap, 411. Airbleed slots 412 are shown. The subgap 411 in combination with theferrite subpoles and ferrite back bar closure 430 form an efficientmagnetic circuit, which when energized with an electrical current incoil 420; drives magnetic flux through the highly permeable surface thinfilm layer 404, which spans the subgap from one ferrite member to theother. The flux that is driven across this surface film intercepts thearbitrary shaped gaps 414 that have a stray field that impresses fluxonto the recording medium. The detailed shape of the gaps 414, as seenin FIG. 4C, and the write current waveform determine the marks that arerecorded onto the medium. As seen in FIG. 4A, ceramic members 440 serveas non-magnetic element spacers and in one embodiment can serve as atape bearing surface. Glass bond area 441 of FIG. 4C and FIG. 4D,separates the active head element 450, of FIG. 4B and FIG. 4C, from theceramic spacers 440 on either side as shown in FIG. 4C. The gap pattern414 may be formed as part of the plating process of the surface film404, or they may be formed in a subsequent photolithographic etch orother etch processes such as that taught in the '533 patent. The surfacefilm may be etched or deposited into two non-interacting parts. Surfacefilm 404 is magnetically active as it is part of the active head element450. As shown in FIG. 4D, surface film 405, although of the same depositas surface film 404, is inactive as it has been separated from 404 byslot 407. Slot 407 may be created by broad beam ion milling or byselective plating. Isolation element slot 407 is typically 30 to 70microns in width and serves to completely decouple 405 from 404 and torender 405 inactive as a magnetic flux conduction element. However, film405 does act as a tape bearing member. Such details may be seen in thecross-section of FIG. 4D. This is the subject of the Wear Pads patentapplication which is a continuation of '528.

Therefore, with full consideration of the background art described, itis desired to find a way to make an even more efficient multi-elementservo head that will have even lower inductance and, hence, higherfrequency capability and which will serve as a superior platform for themanufacture of complicated multi-gap structures envisioned in the futureof magnetic servo tracks for high track density tape products.

SUMMARY OF THE INVENTION

The present invention relates to a low inductance, high efficiencysurface-film, thin film magnetic recording head and a method offabricating the same. This head is created by using a vertical planarprocess thin film head wafer technology in combination with a horizontalplanar process surface film head processing at the row bar level.

An arbitrary gap pattern head assembly for the writing and verificationof servo patterns on tape is provided which utilizes, in itsmanufacture, two major thin film process planes and comprises: (a) uponthe first major process plane is made, a thin film subgap subpolesubstrate structure and from which obtains one or more bar structures,each one having one or more recording elements each element with twodriving subpoles, one nonmagnetic subgap, a thin film coil or portionthereof and (b) upon the second major process plane, which is generallyorthogonal to the first major process plane, is made a magneticallypermeable thin film which spans at least from one subpole to the othersubpole of each recording element and which contains an arbitrary gapstructure suitable for writing or reading on high track density magnetictape. A method of batch fabricating the same where such methods enablethe fabrication of arbitrary slanted gap recording heads commonlypracticed in the video recording art or complex servo pattern gaprecording heads practiced in the high density tape data storage market.

Modified slanted gap structures of the timing based servo writer toimprove efficiency and linearity of the servo signal are also described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view cross-section of a prior art vertical planarprocess thin film head.

FIG. 1B is a top planar view of the prior art vertical planar processthin film head.

FIG. 2A is a side view cross-section of a prior art horizontal planarprocess thin film head by Aboaf, et. al.

FIG. 2B is a top view of the prior art horizontal planar process thinfilm head by Aboaf, et. al.

FIG. 3A is a perspective view of a prior art ferrite/composite surfacethin film head by Albrecht et. al.

FIG. 3B is a top view of a prior art surface thin film gap pattern byAlbrecht et. al.

FIG. 4A is a perspective view of a prior art surface thin film head ofDugas.

FIG. 4B is a perspective view of a prior art surface film head elementof Dugas.

FIG. 4C is a top planar view of a prior art surface film head element ofDugas.

FIG. 4D is a cross section of one element of the prior art head showingthe flux carrying active film member as distinct from the tape bearinginactive film member by Dugas.

FIG. 5A is a partial cross section view of the integrated thin filmsubgap subpole substrate.

FIG. 5B is a partial perspective view of the integrated thin film subgapsubpole substrate.

FIG. 5C is a partial perspective view of the integrated thin film servoformat head.

FIG. 5D is a partial cross section view of the integrated thin filmservo head showing the magnetic flux path and the magnetic recordingmedium.

FIG. 5E is a perspective view of the integrated thin film subgap subpolesubstrate.

FIG. 5F is a perspective view of the integrated thin film servo head.

FIG. 6 is a block diagram describing the overall process forconstructing a surface film subgap recording head, the initial waferlevel VPP process and the subsequent HPP row bar level process.

FIG. 7A shows a top partial-view showing two elements of the subgapsubpole substrate and the region in-between the elements.

FIG. 7B shows a top partial view showing two elements of the subgapsubpole substrate and the region in-between the elements and with thesurface thin film disposed thereon.

FIG. 7C shows a top partial view showing two elements of the subgapsubpole substrate and the region in-between the elements and with thesurface thin film disposed thereon and with the gap features placed inthe surface film.

FIG. 7D shows a top partial view showing two elements of the subgapsubpole substrate and the region in-between the elements and with thesurface thin film disposed thereon and with the gap features placed inthe surface film and the region in-between the elements devoid ofsurface film so as to magnetically and electrically isolate the twoelements.

FIG. 7E shows two completed and magnetically isolated elements with anon-active portion of the surface film left in-between the elements toserve as a tape bearing member.

FIG. 8A shows two completed and magnetically isolated elements with aflux focusing aspect to the film with a tape bearing extension in theup-track and down-track regions and with curved gap terminationfeatures.

FIG. 8B shows the minimum amount of surface film required for twocompleted and magnetically isolated elements, one with a flux focusingaspect to the film and both with curved gap termination features.

FIG. 8C is the same as FIG. 8B but with inactive surface film acting asa tape bearing member.

FIG. 9A shows a cross section of a multi-layer coil structure with noapex feature.

FIG. 9B shows a cross section of a multi-layer coil structure with anapex and subgap depth feature.

FIG. 10A is a cross section of a compound subgap subpole substrate.

FIG. 10B is a cross section view of a compound integrated thin filmservo format head.

FIG. 10C is a partial top view of a compound integrated thin film servoformat head.

FIG. 11A is a cross section of a compound subgap subpole substrate.

FIG. 11B is a cross section view of a compound integrated thin filmservo format head.

FIG. 11C is a partial top view of a compound integrated thin film servoformat head.

FIG. 11D is a side view schematic layout of a compound integrated thinfilm servo format head showing the bonding pad layout.

FIG. 11E is a top view schematic layout of a compound integrated thinfilm servo format head showing the bonding pad layout.

FIG. 11F is a perspective view of the compound integrated thin filmservo format head.

FIG. 12A is a top plan view of a subgap subpole layout for a dual gaptiming base head element.

FIG. 12B is a top plan view of a subgap subpole layout for a dual gaptiming base head element where each gap is independently written using aunique element of compound head structure.

FIG. 12C is a top plan view of a subgap subpole layout for a three gaptiming base head element.

FIG. 12D is a top plan view of a subgap subpole layout for a three gaptiming base head element wherein the left hand and middle gaps arewritten by using one unique element of a compound head structure and theright hand gap is written by using another unique element of a compoundhead structure.

FIG. 13A is a top view of the track identification and format schemebased on the large angled azimuthal recording servo format.

FIG. 13B shows, in part, a top view of the transitions on tape of thelarge angled azimuthal recording servo format.

FIG. 13C shows, in part, a top view of the compound subgap subpole headthat can be used to record the transitions on tape of the large angledazimuthal recording servo format.

FIG. 14A is a top view of the track identification and format schemebased on a combination of amplitude and timing based servo formats.

FIG. 14B shows, in part, a top view of the magnetic transitions on tapeof the combination amplitude and timing based format scheme.

FIG. 14C shows, in part, a top view of the compound subgap subpole headthat can be used to record the transitions

FIG. 15A is a top view of the magnetic transitions of a combination twofrequency amplitude servo format.

FIG. 15B shows, in part, a top view of a compound head system which canrecord the combination two frequency amplitude servo format.

FIG. 15C shows, in part, a top view of a another compound head systemwhich can record the combination two frequency amplitude servo format.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is a fully integrated arbitrary gap recording headwhich may contain single or multiple head elements and methods of makingthe same. The present invention enables the formation of a magneticsubgap and subpole row bar substrate from a wafer level process. Thissubstrate is in turn used in a subsequent process in which an arbitrarygap pattern may be formed upon the subgap in-between the subpoles. Thearbitrary gap pattern will be made in a magnetic thin film and will bedriven by magnetic flux emulating from the subpoles. In variousembodiments of the head of the present invention, the structure providesa head with operating efficiencies over prior-art heads andmanufacturing efficiencies over prior art heads. For instance, a head ofthe present invention may provide a highly efficient multi-elementrecording head having a relatively high frequency response suitable foruse as a servo write or a servo verify read head, and suitable for useas a data write head.

In one embodiment, the present invention relates to a low inductance,high efficiency surface-film, thin film magnetic recording head and amethod of fabricating the same. This head is created from theutilization of traditional vertical planar processing (“VPP”), used tomanufacture wafer which is then processed into row bars. The row barsare then processed to accept a ceramic closer piece. A ceramic closurepiece is bonded, and this combination is further processed throughgrinding and lapping operations to specific dimension, surface finishand contour to form a basic head structure which is then prepared forhorizontal planar processing (“HPP”) of the surface spanning magneticthin film. The HPP is used to prepare the basic head gap structureswhich form various embodiments of the integrated head of the presentinvention. The HPP process is essentially a surface film head process.

A result of this overall construction technology and head design is toform an integrated thin film multi-element subgap subpole magnetic headsubstrate upon which is made a surface film head with an arbitrary gap.Also, this process may provide a magnetic recording head having multipleelements wherein each element is separately and individuallycontrollable and isolated from the next. Alternatively, the head mayhave a single driving channel with multiple arbitrary gap channels alldriven by a common subgap subpole and coil system.

The head design of this invention using the VPP and HPP technologies incombination is now explained in detail.

With reference to FIGS. 5A through 5D, an embodiment of a method formaking a head of the present invention is described. The flow chart ofthis process is schematically shown in FIG. 6.

As generally shown in the figures, the method to manufacture a head ofthe present invention includes combining a wafer level VPP process(block 610, FIG. 6) which results in a wafer that can be sub-dividedinto row bars (block 620, FIG. 6) which are in turn used in a row barlevel HPP process (block 630, FIG. 6) to form the finished headstructure (block 640, FIG. 6). In summary, both VPP and HPP thin filmhead techniques are combined to make a versatile arbitrary gap magneticrecording head.

The general VPP as described in FIGS. 1A and 1B of the prior art ismodified to design and manufacture a thin film subgap and subpolesubstrate. The thin film subgap subpole VPP is similar to that as usedin thin film write heads, but is specifically different in terms ofachieving the design requirements of an arbitrary multiple gap patternrecording head. For example, there may be a requirement for new or moreplanarization steps since the subgap layer may be much thicker than atypical record gap. The large gap understructure, which is referred toas the subgap, to distinguish it from the recording gap, is required forsubsequent surface film overlay of a multiple angled gap as used intiming based recording systems such as the Linear Tape Open (LTO) tapeservo system. The subgap must be as large as the span of the arbitrarygap pattern. This invention anticipates and enables further developmentsin timing base recording formats as well combinations of timing andamplitude formats.

After the thin film subgap subpole substrate wafer is created, it isdiced into row bars. In the simplest case there would be a one elementsubgap head substrate array per row bar. Typically, in tape heads, aclosure piece is bonded to the row bar. This structure is then lapped towhat is called gap depth in the case of traditional inductive thin filmheads. However, for this invention, the parameter that is most usefulwill be the coil depth. The term coil depth refers to the distance fromthe lapped surface to the closest turn of the coil lying beneath thelapped surface.

The VPP fabrication operations are now described in detail.

FIGS. 5A and 5B show one embodiment of a low inductance, high efficiencysurface film magnetic recording head substrate of the present invention.The recording head row bar substrate 501 comprises a wafer substrate510, a first subpole 512, a second subpole 514, a subgap 520 (formedbetween the two subpoles 512, 514), and a closure piece 524.

With reference to FIGS. 5A and 5B, the VPP process is described asfollows: the nonmagnetic substrate 510 will typically be deposited witha basecoat 511 of alumina. This basecoat 511 may be polished after itsdeposition prior to the deposition of the first magnetic layer. Next,the first subpole 512 of a permeable magnetic thin film is deposited.This deposition may be by plating or by sputtering or by evaporation orany other suitable means. It may be plated into a well defined patternedpole piece. If sputtered or evaporated, it may be subsequently processedand etched to form a defined pole piece. These processes will typicallyuse photolithography to define a first pole piece. Next a coilinsulating layer 516 is deposited. Next the coil layer 518 is deposited,typically by plating, and defined upon layer 516. A coil insulating andencapsulating layer 517 which encompasses the coil layer 518 is nextformed and may be planarized to form a specific subgap 520 with aspecific subgap length dimension 538. Layers 516 and 517 combine to formthe subgap 520 in the embodiment shown. A second thin film pole piece,514, of a similar magnetically soft permeable material to the first polematerial 512, is deposited onto the coil insulating and encapsulatinglayer 522. Generally, a deposition will connect the second pole 514 tothe first pole material 512 in the back gap region of the head as shown.This connection is made though a window that is opened to expose thefirst pole 512. A thick back coil insulating and encapsulating layer522, typically alumina, is deposited over the entire structure andlapped providing planarization. A window is etched in layer 517 andbonding pads 579 (only one of two is shown) are deposited through to thecoil to provide electrical connection. This latter step is typicallyperformed by plating.

Magnetic subgap 520 spans and defines the distance 538 from subpole 512to subpole 514 and is made from a combination of coil insulating baselayer 516 and coil insulating and encapsulation layer 517 and mayinclude other dielectric layers as required to encapsulate the coil andplanarize the intermediate structure. An overcoat or planarization layer522 is applied over the second pole 514. This overcoat 522 is typicallymade of alumina This overcoat layer 522 may be planarized by a polishingprocess which may also serve as a subsequent bonding plane for theceramic closure piece 524.

It is important to note that other dielectric insulators other thanalumina may be used as required as well as other layering andplanarization techniques could be used. The thick subgaps and subpolesanticipated may have stress and processing issues that require the useof other dielectrics technologies such as a spin coated photoresistreflow layers or other thick film techniques, all of which are in thespirit of this invention.

With the VPP wafer level process now completed, the row bar is slicedout of the wafer substrate and typically a ceramic closure piece 524,normally of the same material as the wafer substrate 510, is bonded tothe row bar. The row bar structure 501 is then lapped to a specifiedcoil height 548 above the coils 518. Closure piece 524 will typically beattached before the horizontal processing operations or may not berequired at all depending on head contour design.

The row bar assembly 501 which results from this process is shown in theperspective view of FIG. 5B. The row bar 501 is lapped and polished tothe proper coil depth 548 or gap depth as appropriate. The newprocessing surface is defined to be that of the horizontal surface plane590. This plane may be flat or have a curvature as part of contourdesign of the head.

Thus, a second major plane of processing, the HPP plane, has now beenintroduced. The new plane, the surface plane of the row bar, exposedsurface 590, containing the subgap and subpole surfaces, is prepared asthe second major plane of processing, the HPP plane, upon which will beprocessed the main magnetic surface film and its arbitrary gap features.With reference to FIGS. 5A, 5B, 5C and 5D, the HPP processing isperformed on the resulting row bar substrate 501, and specifically uponplane 590, and the combined VPP and HPP dual plane process results inrecording head 500.

The HPP fabrication operations are now described.

With reference to FIG. 5C, the HPP will be described. This process turnsrow bar 501 into head 500. With the prepared subgap subpole substraterow bar, the HPP part of the thin film head is initiated by depositing amagnetically permeable thin film 504 on the surface 590 of the row barstructure 501 with a film growth in the direction of direction arrow595, by various methods such as sputtering, evaporation or plating.

This HPP surface film 504 may be plated with gap features and fluxdirecting features. In non-plated cases, special gap and flux directingfeatures are created in a later step, usually with a photo and dryprocess etch step which may also be called a subtractive etch.Alternatively, in the cases of evaporation and sputtering, the gap canbe defined in photoresist. A photoresist wall would represent themagnetic gap, for example. Hence, a positive gap or a wall is made.Subsequently, the magnetic film is deposited over the wall or over thepositive gap material. Since the film is deposited around the gap aswell as on top of the gap wall, the extraneous film may be removed witha lift-off process. In short, like plating, the gap feature is made,however, now it can be deposited over rather than plated up around thepositive gap. In plating, the gap feature is plated around the gapdefining photoresist, and the photoresist is subsequently removed. Inshort, any one of these and other methods may be used in the presentinvention to complete the horizontal planar process such that a magneticsurface film contains arbitrary recording gap features 560 that are welldefined in the surface spanning magnetic thin film 504. As in the '533patent and continuations thereof, a combination of photoresist andfocused ion beam (“FIB”) can yield good arbitrary shaped gaps in suchsurface films.

In one embodiment of the present invention, the magnetically permeablesurface thin film layer is optimally configured to complete a magneticcircuit for each element over the subgap area and in-between eachsubpole of a particular element. Ideally, the elements are magneticallyisolated from one another. As noted in other embodiments a singledriving channel can suffice to drive an array of arbitrary gaps.

The resulting head 500 of FIG. 5C shows the coil depth 548 incombination with the pole lengths 532 and 534, and subgap length 538,determine, in part, the distribution of flux in the film 504 and acrossgaps 564 that form gap pattern 560 that are to be formed onto surface590 as illustrated.

As discussed, gap pattern 560 and other surface film features asrequired may be made by either selective plating or subtractive etchpost deposition technologies or by a lift-off technique.

FIG. 5D is an expanded view of the gap region of FIG. 5C. The magneticflux 568 and 566 is shown by the arrows in the permeable magneticsurface film 504A for a particular state of current 567 in the coil 518.By the nature of the relatively closed path magnetic circuit of thishead, the magnetic flux is most active across the portion of themagnetically permeable magnetic surface film 504A that lies in-betweenthe two subpoles 512, 514 and over the subgap 520. The recording fieldflux 568 is made up of the field lines that leak over the top of gaps560 and intercept the magnetic tape medium 570, backed by tape substrate572, which traverses in the direction shown by arrow 528. To be mosteffective, the distance 565 from the recording medium surface of thetape to the top surface of film 504A and 504B should be very small.Typically, distance 565 is on the order of a few nanometers.

Noteworthy in FIG. 5D is that the film 504 can extend past the subpoles.The film portion 504B extending past the subpoles 512, 514 will not behighly magnetized and contains no gap features or other features thatwould write marks onto the tape. It may serve to stabilize the tape asit transverses across the head. Such non-energized surface film areascan play the part of a stabilizing bearing if properly designed. Filmportions 504A on top of and in-between the subpoles will carry most ofthe magnetic flux.

FIG. 5E shows a perspective view of the row bar assembly 501 after theVPP process is completed. FIG. 5F is the same as FIG. 5E but shows film504 and gap pattern 560 resulting from the HPP process described above.Recording head 500 is the result of the combined VPP and HPP dual planeprocess.

In order to make the servo read signal more uniform from one track edgeto the other, the servo write signal needs to be written uniformly fromone track edge to the other. In one embodiment, the patterns may includetermination boxes having circular or elliptical features of the typedisclosed in PUB. APP. 20040109261, in order to more effectively containsufficient magnetic flux in the write gaps.

Consideration must be given to the engagement of the media against ahead having a non planar surface while minimizing the complexity ofproviding the air bleed slots if they are required. In addition, whenworking with components of this scale, consideration must be given tothe techniques utilized to impart and define the thin film layer so thatmechanical shear or peeling of the film is not induced by the tape'smotion as the tape hits the edge of the film on the tape bearing surfaceof the head. Hence, in one embodiment, wear pads as disclosed in theDugas patent application, PUB. APP. NO. 20030039063, WEAR PADS FORTIMING-BASED SURFACE FILM SERVO HEADS, Published Feb. 27, 2003, which ishereby incorporated in full by reference, may be used for optimizing thehead-to-tape media interface.

An arbitrary gap pattern 564 in FIG. 5C is formed in the subgap betweenthe two subpoles and is defined by the exact geometry of the gaps 560.This is analogous to FIG. 3B and FIG. 4C. The recording head 500 mayinclude one or more elements. That is, the recording head 500 may havemultiple gap patterns, each pattern or pattern grouping forming a singleservo band element.

These heads may be used to write information on or read information froma magnetic media such as tape. The read head application will be studiedand is anticipated but is not emphasized herein. The write headapplication, optimization for an arbitrary format writer, will beemphasized.

While the description of the invention will be in terms of servo writingtape with arbitrary servo patterns and hence arbitrary gap features,this invention may be applied to other write head applications and readhead applications as appropriate.

As will be recognized by those skilled in this art, these subpoles andthe subgap may all be made thicker as compared to traditional dataheads. The size of the subgap and subpoles are determined by the designand span of the arbitrary shaped gaps. For smaller gap layouts, the spanof the subgap and subpoles will be correspondingly smaller than that forlarger span gap layouts. Large span gap pattern layouts would includesuch gap patterns as the LTO timing-base gap pattern and the IBM 3592timing-base gap pattern and the IBM 3570 timing-base gap pattern. Forexample, the LTO dual gap pattern is about 20 microns from one gap tothe other at one end of the servo track and is about 70 microns at theother end of the servo track. The track is about 190 microns wide. Hencethese gap patterns have a span on the surface of the head in the rangeof 70 to 200 microns over the subgap regions and hence require a subgapspan of about the same area, i.e., 70 by 200 microns. New timing-basegap designs may decrease this span considerably and will allow formagnetically driven subgap thicknesses in the range of from 20 to 50microns or less.

In certain applications of the head as shown, there is no apex point andthere is no slope in the second pole 514 down to an apex point. Afeature of this invention is the distance of the first coil 518 prior tohorizontal surface film processing. This distance is called the coildepth 548. The coil depth 548, the pole lengths 532 and 534, incombination with the subgap length 538, serve as magnetic designparameters in terms of the performance of the head and the consistencyof the performance from head to head performance.

In summary of the basic invention, the VPP operations have a film growthdirection denoted by direction arrow 585 (FIGS. 5A and 5B) from thewafer surface whereas the HPP operations have a film growth in thedirection denoted by direction arrow 595 (FIG. 5C) which shows thedirection of film growth from the row bar surface 590. Direction arrows585 and 595 are perpendicular to one another. Direction 585 shows thegrowth of the subpoles and subgaps, and direction arrow 595 shows thegrowth of the magnetic surface film in which are embedded the arbitrarygap features.

Hence, this invention uses two major process planes which are orthogonalto one another and which in combination form a head structure of a headmanufacturing process to produce a recording head that may containmultiple arbitrary gaps and multiple arbitrary gap arrays. Such a headwill be of very low inductance as compared to the prior art heads and,hence, will have a fast rise time and high frequency response.

A top view of the head and its surface features is now described.

FIG. 7A shows a top view of two elements 580, 581 of the subgapsubstrate row bar of FIG. 5A with the subgap region 520 and the subpoles512 and 514 shown for each element, respectively. Also shown forreference are basecoat 511, overcoat 524 and intermediate dielectricswhich in combination make up subgap 520, as was previously shown. Theentire surface 590 is the prepared second processing plane upon whichHPP will be performed.

FIG. 7B shows the same structure as FIG. 7A, but with film 504 depositedon the top of the surface 590. The subgap region 520 and the subpoles512 and 514 are shown for reference.

FIG. 7C shows the same structure as FIG. 7B but with the timing-base gappatterns 564 shown in film 504. The gap patterns 564 include circulartermination features 562, per the discussion of the prior art, PUB. APP.NO. 20040109261. The subgap region 520 and the subpoles 512 and 514 areshown for reference. If the film 504 spans from one element to the next,it would enhance stray flux, shunt flux around the gap features andcause channel to channel cross talk in some applications.

FIG. 7D shows the same structure as FIG. 7C with the surface filmremoved from the area in-between the elements. In this design, theelements 580 and 581 are isolated, and the film 504 is extended over thesubpoles 512, 514 so that their edges of the subpoles are not in contactor in near contact with the tape medium. Edges in contact with the mediacould write stray marks on the recording medium. Direction arrow 528shows the direction of tape motion in the up-track and down-trackdirections.

FIG. 7E is the same as FIG. 7D but shows a more contiguous surface filmpattern that has been separated into active film component 504A and 504Band inactive film 505 which serves merely as tape bearing surfaceco-planar to the active film 504. The separation is caused by slot 507that is typically tens of microns wide.

FIG. 8A shows a more aggressive flux guiding design. Elements 580 and581 have flux guide feature 571 which makes a magnetic boundary thatlimits flux leakage around the gap features delivering the maximumamount of flux generated in the subpoles to the gap region. The fluxguiding may reduce the required ampere-turns and may also serve to writeuniformly across the track width of the gap feature. As per thediscussion of FIG. 5D, the surface film 504B outside of the drivingsubpoles 512, 514 is not highly magnetically active and can serve as atape bearing member. Curved termination features 562 are shown andprovided for track edge support as well as non-writing magneticterminations to the gap edge per the discussion of PUB. APP. NO.20040109261.

FIG. 8B shows the minimum amount of surface film required to completeelements 580 and 581. Curved terminations 562 are used. For purposes ofillustration, channel 580 is shown without focused flux guiding andchannel 581 is shown with focused flux guiding.

FIG. 8C is the same as FIG. 8B but has the isolated channels in a sea ofinactive magnetic thin film 505. The inactive film 505 provides a morecontiguous bearing surface for the tape medium.

Whether there is an apex or a true gap depth in the sense of a standardintegrated thin film head is not a limiting feature of this head. If asecond pole with well defined apex and gap depth is required for designor processing considerations, it would not be considered out of thescope of this invention.

A multi-layer coil 518 is shown in a three layer configuration in FIG.9A. Similarly, a single coil layer may or may not have an apex withsubgap depth without restriction. An example showing multi-layer coilswhich may also require an apex and gap depth approach is shown in thecross-section of FIG. 9B. The apex point 521 is analogous to apex point121 of FIG. 1A. In this case, 548 is now the gap depth rather than thecoil depth but relates to a specific coil depth by the mask layout.

Multi-module heads which are combination assemblies of two or more headmodules are fully within the scope of this invention. If the headmodules are made completely separately, the alignment precision betweenthe two heads and their patterns will be on the order of about 1 um. Adual head system such as this can have gap patterns aligned to oneanother to a degree that is only as good mechanical alignment techniqueswill allow for. For some applications, such a tolerance will be morethan sufficient. In other applications, the gap pattern of one head mustbe more accurately matched to the gap pattern of the other head.

Such heads can take distinct advantage of the construction taught hereinto realize novel multi-element structures. They may be madeindependently as single modules and mechanically aligned together, orthey may share a common HPP deposition and patterning process. Thelatter will make a more accurate head assembly if pattern-to-patterntolerances are required.

Because the invention provides for a method of making heads with anyarbitrary gap pattern, dual head modules whose gap features work incombination with one another to provide unique servo precision may bemade in accordance with the principles of the present invention. Onesuch application is that of DC pre-erasing the track ahead of theuni-polar current pulsed timing-base structure as in patent applicationSer. No. 10/768,719 by Dugas. Other applications may include double timebase patterns, timing base and amplitude base combinations, timing andtiming combinations and other arbitrary gap combinations that giveunique servo patterns on tape, among other applications. More complexpatterns that can take advantage of the head construction of thisinvention are, in particular, the compound head structure of FIGS. 12and 13, shown in US Patent Publication Number US2003/0151844 A1 by JamesEaton, Wayne Imaino, and Tzong-Shii Pan, published Aug. 14, 2003. Inparticular, in this patent application, both triple and quadruple gappatterns are shown which are similar to the LTO gap pattern in style.While the Eaton patent publication does teach a dual head servo system(FIG. 13 of said reference) it does not teach a head design per se anddoes not teach a head design that can accomplish the dual head modulealignment with high precision. A similar triple gap servo pattern is thesubject of U.S. Pat. No. 6,542,325 BI by Richard Molstad, Michael Kelly,and Douglas Johnson. This patent, '325, teaches the three gap timingbase design similar to Publication '844 wherein any two of the threegaps are parallel and where the third gap gives the differentialazimuthal signal with respect to the two parallel gaps, but thisapplication does not teach a compound head application thereof.

FIG. 10A shows a cross section of two subgap row bars 501 bondedtogether to form a dual module substrate for HPP processing from one HPPmask operation. In this case, the substrates are bonded togetherback-to-back as shown with the bond pads facing outwards. The two rowbars, each similar to 501 as previously described in FIGS. 5A-5F, arebonded together prior to the HPP steps. The boundary between the twoheads 599 may be made with a precision bonding agent or glue that isimpervious to solvents used in cleaning and which will be compatiblewith the subsequent processing steps. We now have a 501L (left) and a501R (right) as shown in FIG. 10A and in analogy to the previousdiscussion of FIGS. 5A-5F. The other elements, similar to FIG. 5A and5B, are subgaps 520L and 520R, subpoles 512L and 512R and 514L and 514R,coils 518L and 518R, bond pads 579L and 579R, and optional closures 524Land 524R, among other features as described in FIGS. 5A-5F. Thedirection of film growth processing is shown by 585L and 585R. Thelabeling of the elements is not meant to be as exhaustive as theprevious descriptions of FIGS. 5A-5F.

The two row bar modules are now fixed together to form a compound HPPsubstrate module that has tolerances on the order of 1 um ith respect toeach other in terms of critical dimensional alignments. The substratemay have been bonded at wafer level or at the row bar level. The rowbars could have come from one wafer with a single VPP process or couldhave come from two different wafers with differing subgap subpoledesigns. In any event, the compound row bar is lapped and polished andprepared for HPP processing. The substrate 1001, while made of twodistinct row bars with left and right handedness, has a commonhorizontal processing plane 590, the same as discussed in FIGS. 5A, 5Band 5C.

The HPP process is now made a common process for the compound row barassembly with a common deposition, common mask operations, and commonetching or patterned plating operations such that the down-track andcross-track gap pattern elements can all be made of a precision to about0.1 um to 0.05 um with respect to each other. All of the above will beanalogous to FIG. 5, and all the processing taught therein appliesherein to the compound head of FIGS. 10A-10C. FIG. 10B shows thiscompound head after HPP processing in cross section. Note film 504 iscommon and hence is not labeled as to left or right. The same applies tocommon horizontal processing plane 590. The important distinction of acommon mask is shown by mask plate 1600 carrying head gap features 1664Land 1664R corresponding to the left and right side head gap patterns,564L and 564R, respectively.

FIG. 10C shows a top view of two channels of each head element. As shownin FIG. 10A and 10B, the two substrates 510 are now labeled as 510L and510R. The other features as those shown in FIG. 5 are likewise labeledby their handedness. The VPP processes could be common for each head rowbar, and each row bar could have come off the same wafer, if the designallows for that. Alternatively, if the subpoles and subgap each have adifferent design to carry a different gap pattern 564, that is if 564Land 564R are different enough require different subgap substrategeometries, then each row bar substrate, 501L and 501R of FIG. 10B,could come from differing VPP processes with differing poles and subgapspecifications to match the requirements of gap patterns 564L and 564R,respectively.

The head shown in FIG. 10C shows a double LTO pattern, for illustrationpurposes only; any arbitrary gap patterns could be used according to therequirements of the servo design. The head of FIG. 10 was made by matingthe substrates back-to-back. In this way, the bonding pads are eachfacing outward as shown in 579L and 579R of FIG. 10B. In such anassembly, the flex leads can be easily managed.

FIG. 10C also shows the typical spacing of the heads. Dimension arrow1010 is from about 2 mm to about 4 mm in length. This compares to thedimension 1020 of about 10 μm to 200 um. The exact thickness of thelayers will depend on the exact arbitrary gap layout. This dimension,1020, represents the deposited thicknesses of the subpoles and subgaps,coil layer, undercoat and overcoat layers and all the layers required ofthe VPP level design. Accordingly, the drawings cannot be shown to exactscale.

The larger dimension 1010 is due to the fact that the substrate materialtypically comes in relatively thick wafers typically from 1 mm to 2 mmin thickness. The substrate could be ground thinner after processing tominimize this distance. This is called back-side thinning and issometimes a practice used in semiconductor and thin film headtechnology. However, if the goal is to have very closely spaced gappatterns in the up-track and down-track directions, another approachwould be to reverse the assembly as shown in the head of FIG. 11A.

FIG. 11A is a cross section showing the row bar substrates abutted sothat the second poles 514L and 514R are placed proximate to one another.This is opposite to the substrate back-to-back process as described inFIG. 10A. In this configuration, closure 524 is not used, and overcoat522L and 522R may be minimized. Also in this configuration, it may berequired to place a highly conductive layer on or adjacent to theboundary 599 between the two head modules to minimize any cross talkfrom one to the other during writing or reading operations. For example,a thin film of Copper may be deposited onto the top of the overcoatlayer 522L or 522R as required. Alternatively a thin laminate of Copperfoil, for example 1 mil (0.001″) foil, may be placed in between themodules. The Copper will serve to provide eddy current shielding betweenthe two head modules. Magnetically permeable shielding could be used aswell or in combination with Copper. Such shielding techniques are wellknown.

FIG. 11B is a cross section of the completed head. Exactly as in FIG.10B, the HPP is shown to be accomplished with the common deposition offilm 504 and common mask 1600 as schematically shown with the left 1664Land right 1664R gap patterns as would be on the mask.

FIG. 11C is a top view of this head showing a much closer distance 1110between the patterns as compared to that same distance 1010 which wasobtained through the technique described in FIG. 10A-10C. Again, thepatterns schematically represent a double LTO pattern although any setof arbitrary gap patterns could be used. Note that distance 1110 fromthe center of one gap pattern to the center of the other is now only afunction of the thin film designs and not a function of the substratethickness. Hence, distance 1110 is now much shorter as compared todistance 1010.

In timing based servo systems the instantaneous speed variation (ISV)effects are to be minimized. In some servo signal detection designsshorter span from one gap pattern to the other may be advantageous inachieving a more robust compound servo as shown in these examples. Inother servo signal detection schemes, a longer base line may be desired.Thus depending on the servo signal scheme, compound patterns can takeadvantage of either of the techniques taught in FIG. 10 or FIG. 11.

The compound substrate scheme of FIG. 11A leaves the bonding pads facinginward. The bonding pads 579L and 579R were not shown in FIGS. 11A and11B due to this difficulty. An offset pad configuration can solve thisapparent problem. One offset pad configuration is shown in FIGS. 11D and11E.

By placing the bonds pads 579L and 579R in an area to either side of theelements, this issue may be mitigated and managed as shown in FIGS. 11Dand 11E. In FIG. 11D, the leads are brought to one side of the row barchip and, hence, when the row bars are mated to form a compound row bar,the elements each expose the bonding pads to an open manner such that aflex circuit may be bonded in a simple and unopposed fashion. This isfurther illustrated in FIG. 11E. A projection of this compound head isfurther illustrated in FIG. 11F.

Yet another example of the applicability of the compound subgapsubstrate is to use individual writing of individual gap elements toproduce a complex arbitrary servo pattern. In some servo designs where alonger up-track to down-track spacing is desired, the compound headassembly of FIG. 10A-10C may be used. That design uses the back-to-backsubstrate approach. In other designs where a very close spacing isdesired, the compound head assembly of FIG. 11A-11E may be used.

As discussed the head can be made into a one dimensional array ofelements, as per FIG. 5F, or the head may be made into a compoundstructure with a two dimensional array of elements as shown in FIG. 10Cand FIG. 11C.

FIGS. 12A-12D show other examples of the recording head of this patent.FIG. 12A shows an LTO type pattern laid out in a single subpole subgapelement. The example represents an application of the head of thisinvention to an existing product gap pattern. FIG. 12B shows the samedual gap LTO pattern as shown in FIG. 12A but now each gap can beaddressed independently through the use of the compound head techniquesdescribed in FIG. 11A-11E. The LTO pattern and the subgap and subpolesare shown more to proper scale in these figures as compared to theprevious figures. The advantage of this technique as taught in FIG.11A-11E is that the true LTO pattern, using a 50 um center-track tocenter-track spacing with six degree angles and with a 190 um trackwidth, can actually be made such that each gap can be independentlywritten, if a servo system requires it. Bond line 599 is schematicallyshown and the surface film 504 is shown having been deposited andpatterned in a common process. The gap pattern 564 is distinguishedfurther for this embodiment as being made up of left handed gap 560L andright handed gap 560R as shown in FIG. 12A. FIG. 12B shows where thesame gap pattern 564 of FIG. 5A has been made across two independentsubgap subpole structures, thus each gap 560L and 560R may be writtenindependently, respectively, in association with driving coils 518L and518R not shown. All of this is in the spirit of the construction taughtin FIGS. 10A-10C and in particular in the spirit of the FIGS. 11A-11Fwhere a much closer yet independently driven element separation, in theup-track and down-track directions, is taught.

FIG. 12C shows a three gap LTO type of pattern as previously referenced.In this pattern, the three gaps can lie within one subgap system asshown. Again, the invention presented herein can replace theferrite/ceramic composite structure of prior art FIGS. 3A-3B and FIGS.4A-4D. However, using the techniques taught in FIG. 11A-11D, the gappatterns may be split apart and written independently as shown in FIG.12D. Such independently electrical control of each gap of a multi-gappattern could be of use in advanced servo systems and has been shown inPublication '844 by Eaton, Imaino, and Pan, of IBM. In FIGS. 12C and12D, the middle gap 560M is distinguished accordingly along with 560Land 560R. The three gap structure is shown to be divided and remodeledas a dual gap structure for the left hand module and a single gapstructure for the right hand module. All of this is in the spirit of theconstruction taught in FIGS. 10A-10C and in particular in the spirit ofthe FIGS. 11A-11E where a much closer yet independently driven elementseparation, in the up-track and down-track directions, is taught.

FIG. 13A illustrates an application of the head of this invention tothat of the Large LAAZR patents applied for by Schwarz and Dugas, havingSer. No. 10/793,502. This is a combination amplitude base and timingbase servo approach where the track identification, such as shown inFIG. 13A, is determined by the distance from the large timing pattern1564R to the amplitude pattern 1564L. These patterns have a precisesubmicron relationship to each other and therefore must be made from acommon masking operation. A section of how this would appear on tape isshown in FIG. 13B, and a schematic layout of the compound head is shownin FIG. 13C. In FIG. 13C, the zigzag azimuthal amplitude gap pattern564L is shown in the left hand head module driven by subpoles 512L and514L, and the large structure azimuthal timing gap pattern 564R is shownin the right hand head module and is driven by subpoles 512R and 514R.Boundary 599 is shown along with surface film 504 with the understandingthat the gap patterns 564L and 564R are processed into common film 504in one photolithographic step. Film 504 is later separated or can begrown as shown in a plating operation.

FIG. 14A shows yet another timing base and amplitude base combinationconcept that can be made practical through the use of the concept taughtin this invention. FIG. 14A shows timing track identifications TrackID1, Track ID2, and Track ID3. It also shows an A length and a B lengthrelated to each ID label, for example Track ID1A and Track ID1B, foreach head servo track 1580, 1581, and 1582, respectively. The pattern onthe tape is shown in the magnetic transitions 1564L and 1564R of FIG.14B. The head that can make these patterns is shown in FIG. 14C and isanother example of a specific embodiment of the heads described in FIG.10A-10C and FIG. 11A-11F. Again we have independent driving poles pairs,512L and 514L, and 512R and 514R, respectively, which drive gap patterns564L and 564R independently as shown.

FIG. 15A-15C shows yet another embodiment of the compound heads of FIGS.10A-10C and FIG. 11A-11F. In this scheme, a pure amplitude pattern isshown to be made identically from two different embodiments. Themagnetic transition pattern of FIG. 15A is made up of transitionpatterns 1564L and 1564R. The frequencies of the two patterns aredifferent, and when a servo read head is parked across each half-track,it can be determined that servo read head is sensing the two frequenciesin a particular weighting. In this example, the frequency of pattern1564R is twice that of 1564L. This set of magnetic transitions as shownin FIG. 15A can be made from the head shown in FIG. 15B or from the headshown in FIG. 15C. In the case of FIG. 15C, the elongated gap pattern564L is overwritten by the segmented gap pattern 564R. Once again, eachgap pattern resides in an independently controlled subgap subpolesystem, and the patterns are made on the compound substrate in onephotolithographic step as described in detail in the discussion relatingto FIGS. 10A-10C and FIGS. 11A-11F.

One skilled in the art could also recognize that the compound substratecan be made of just one substrate wherein one subgap system withassociated subpoles is fully planarized and then another entire systemis made with another round of VPP right on top of the previous system.While this would be an extraordinarily complicated process, it is notout of the question and may at some point in time be a useful strategyto employ. Alternatively, multiple stacks of the present invention canbe conceived and made to accomplish a combination of multiple gapmodules of multiple channels for various data storage purposes for bothread and write head applications.

Both single and multi-coil version of this head invention may be usedfor different applications and should be considered within the scope ofthis invention. A single coil can span and drive several servo channelpatterns or each channel pattern may have its own drive coil. Similarly,the write driver can drive all channels with one signal or amulti-channel write driver may be used to drive individual channelswhich have a write driver channel. Delayed timing from one channel tothe next may be employed. Channel-to-channel isolation is assumed asrequired for these write driver applications.

Per the previous discussions, various methods of film deposition and gapdefinition may be used without limitation.

Those skilled in the art will further appreciate that the presentinvention may be embodied in other specific forms without departing fromthe spirit or central attributes thereof. For instance, while thediscussion of the invention was described in terms of servo writing tapewith arbitrary servo patterns and hence arbitrary gap features, thisinvention may be applied to other write head applications and read headapplications as appropriate. Furthermore, while the disclosure generallyconcentrates on embodiments of the present invention as it applies tomulti-channel, linear tape recording, some aspects of the inventionsherein may be applied to magnetic track transitions, angled to thetransverse axis, as may be found in azimuthal recording schemes.

The foregoing description of the present invention discloses onlyexemplary embodiments thereof, it is to be understood that othervariations are contemplated as being within the scope of the presentinvention. Accordingly, the present invention is not limited in theparticular embodiments which have been described in detail therein.Rather, reference should be made to the appended claims as indicative ofthe scope and content of the present invention.

1-37. (canceled)
 38. A method of formatting magnetic media comprising:providing an integrated thin film magnetic recording head having atleast two recording elements, each recording element comprising: firstand second magnetically permeable thin film subpole members, separatedby a substantially low permeability subgap member, an integratedelectrically conductive coil structure embedded in part within thesubgap member and in part in-between the first and second subpolemembers, the subgap member and subpole members forming part of amagnetic circuit; and a magnetically permeable thin film layer spanningfrom at least the first subpole member to the second subpole member andincluding one or more arbitrary recording gap patterns; wherein the atleast two recording elements are substantially magnetically isolated andelectrically independent of one another, each recording element having aunique coil; and wherein the direction of film growth of themagnetically permeable thin film layer is substantially orthogonal tothe direction of thin film growth of the first and second magneticallypermeable thin film subpole members; and passing magnetic media over themagnetic recording head to format the magnetic media based on the one ormore arbitrary recording gap patterns.
 39. The method of formattingmagnetic media of claim 38, wherein the film growth of the subpolemembers and subgap member is on a wafer level plane.
 40. The method offormatting magnetic media of claim 39, wherein the film growth of themagnetic thin film layer is on a row bar level plane.
 41. A method offormatting magnetic media comprising: providing an integrated thin filmmagnetic recording head having at least one recording element comprisingfirst and second magnetically permeable thin film subpole members,separated by a substantially low permeability subgap member, anintegrated electrically conductive coil structure embedded in partwithin the subgap member and in part in-between the first and secondsubpole members, the subgap member and subpole members forming part of amagnetic circuit; and a magnetically permeable thin film layer spanningfrom at least the first subpole member to the second subpole member andincluding one or more arbitrary recording gap patterns; wherein the thinfilm layer has been selectively removed in portions so as tomagnetically isolate each of the recording elements; and wherein thedirection of film growth of the magnetically permeable thin film layeris substantially orthogonal to the direction of thin film growth of thefirst and second magnetically permeable thin film subpole members; andpassing magnetic media over the magnetic recording head to format themagnetic media based on the one or more arbitrary recording gappatterns.
 42. The method of formatting magnetic media of claim 41,wherein the magnetic recording head comprises a plurality of recordingelements which share a common coil.
 43. The method of formattingmagnetic media of claim 41, wherein the magnetic recording headcomprises a plurality of recording elements, each having a unique coil.44. The method of formatting magnetic media of claim 43, wherein themagnetic media is formatted with a timing based servo pattern.
 45. Themethod of formatting magnetic media of claim 43, wherein the magneticmedia is formatted with an amplitude based servo pattern.
 46. The methodof formatting magnetic media of claim 41, wherein the thin film isstructured to focus the flux from the subpole members across the thinfilm lying on top of the subgap member so as to increase the fluxdelivered to the one or more arbitrary recording gap patterns.
 47. Themethod of formatting magnetic media of claim 41, wherein the coilstructure is a single layer coil.
 48. The method of formatting magneticmedia of claim 41, wherein the coil structure is a multi-layer coil. 49.A method of formatting magnetic media comprising: providing anintegrated thin film magnetic recording head having at least onerecording element comprising: first and second magnetically permeablethin film subpole members, separated by a substantially low permeabilitysubgap member, an integrated electrically conductive coil structureembedded in part within the subgap member and in part in-between thefirst and second subpole members, the subgap member and subpole membersforming part of a magnetic circuit; and a magnetically permeable thinfilm layer spanning from at least the first subpole member to the secondsubpole member and including one or more arbitrary recording gappatterns; wherein the direction of film growth of the magneticallypermeable thin film layer is substantially orthogonal to the directionof thin film growth of the first and second magnetically permeable thinfilm subpole members; and passing magnetic media over the magneticrecording head to format the magnetic media based on the one or morearbitrary recording gap patterns.
 50. The method of formatting magneticmedia of claim 49, wherein the film growth of the subpole members andsubgap member is on a wafer level plane.
 51. The method of formattingmagnetic media of claim 50, wherein the film growth of the magnetic thinfilm layer is on a row bar level plane.
 52. The method of formattingmagnetic media of claim 51, wherein the magnetic media is formatted witha timing based servo pattern.
 53. The method of formatting magneticmedia of claim 52, wherein the thin film is structured to focus the fluxfrom the subpole members across the thin film lying on top of the subgapmember so as to increase the flux delivered to the one or more arbitraryrecording gap patterns.
 54. The method of formatting magnetic media ofclaim 52, wherein the coil structure is a single layer coil.
 55. Themethod of formatting magnetic media of claim 52, wherein the coilstructure is a multi-layer coil.